Motor system



March 21,

93 r c. P. SWEENY 2,151,053

MOTOR SYSTEM Filed Dec. 17, 1956 gwue/wto o Patented Mar. 21, 1939 UNITED STATES PATENT OFFICE Vickers, Incorporated ration of Michigan Detroit, Mich, a corpos ucauon December 17, 1935, Serial No. 116,430 Claims. (o i.' 112-239) This invention relates to electric motor sys-fjj.

tems, and more particularly to. motor system of the electric gear type in which rotation of the 5 rotor of one motor causes'the'rotors clone or 6 more motors at a distance from-the first motor,

to follow the rotor of the flrst motor.

An object or the presentiinvention is to pro- A vide an electric motor system in which the rotor of a distant motor accuratelylollowsthe rotor l0 of a control motor.

Another object oithe invention is to provide an electric motor system -o1'-"theSelsyn type in which the controlled motor has high torque 15 motor andin pulling into step'or phase with-the control motor, and in torque can be controlled. V V v A further object is toprovide such a motor system in which the controlled motor will 'main- 20 tain exact step with the control motor under load.

A still iurther object of the, inventionis to' -'apply direct current energizationto' the motors of an electric gear to increase the torque of the I controlledmotors and therefore the load under 25 which they'will maintain substantially exact corresponding positions with respectto the control motor.

Other objects and advantages of the invention will appear in the following description of a so preferred embodimentof the invention shown in the attached drawing'ofi which the single figure is a schematic drawing ci a motor system including two motors. I

Referring to'the drawin at similar mats 35 i0 and H are provided with primary windings A energized from a source of alternating current through the conductors. A1, A2; control windings B energized from asource of direct currentthrough the conductors B1, B2; and sec-- 0 ondary windings C connected together through slip rings I2, I 3 and. i4, brushes l5, l6 and I1 and. conductors I8, I 9 and 20.

The primary winding Aof each motor is usually positioned on the stator member and is 45 shown as a four-pole single phase winding although such winding may be positioned on eitherr member of the motor and may have any number of poles desired. The secondary winding C is positioned upon the motor member which is 50 relatively rotatable with respect to the primary winding and usually upon the rotor member as shown. Preferably this-winding is a Y connected phase winding although other connections such as the A connection shown in my 00- 55 pending application, Serial No. 72,632, filed April which the value-oi this 3, 1936, of which this application is a continua- Ition in part,may be employed. The disclosure {of the present application differs from Figure 20 of the above mentioned copending application only in that a Y connected secondary isemployed 6 instead of a A connected secondary and a rheostat 2| is provided to vary the direct current energization of the motor. The Y connection is in general preferable because undesirable circulating currents in the secondary sometimes 00- 10 our with a A connection, which currents in-' crease the power taken by the motor without producing any useful result. both during rotation of therotoroi' the control I The primary and secondary windings A and C of the two motors react upon each other in the normal manner of electric gear systems in which the displacement of the rotor of one motor with respect to that of the other causes resultant voltages to be induced in the two secondary windings. These resultant voltages cause power currents to circulate between these windings which tend to cause the rotors to move into step. In the present system, however, the primary windings are energized to produce less than the normal magnetizing flux oi the motor when only 4 the primary windings. are energized and a supplemental direct current energization by the control winding 13, which is preferably positioned upon the same member as the primary winding, is employed tobring the iron of the motor to normal saturation for the motor. That is, the voltage applied to the primary winding A is not suiilcient to cause normal saturation of the iron of the motor, and applying the direct current energization to'the control winding B brings the iron to normal saturation, thus decreasing the effective reactance of the primary winding and causing larger currents to flow therein.

The conductors of the control winding are preferably so positioned, that no resultant volt- 4 ages are induced therein by the alternating ilux produced by the energization of the primary winding, so that no substantial alternating currents flow in these windings when the rotors are in corresponding positions. "Howeverfwhen the rotors of the two motors are displaced relative to each other, the fields caused by currents cirtorque oi the controlled motor. It will be apparent that the latter effect does not depend primarily upon the direct current energization, since the provision of interconnected windings, such as the control windings B, would provide additional paths for the circulation of power currents between the two motors upon relative displacement of the rotors thereof even if the control windings are not energized by direct cur rent. The direct current energization of the control windings B does however decrease the available torque of the controlled motor independently of circulating currents in the control windings since it causes larger currents to flow in the primary and secondary windings and the various interactions discussed above between the various windings are made possible by the employment of distributed windings in slots of the motor members and the absence of salient poles. The direct current energization provides a means for varying the available torque of the controlled motor. This variation can be accomplished by any desired means of varying the direct current voltage, for example, by the variable resistance shown. In most installations, however, the amount of direct current energization will be predetermined and the correct value of direct current voltage supplied with no means for ad justing this voltage.

While I have described the invention with respect to two motors, either one of which may be the control motor driving the other motor, any number of motors may be similarly interconnected so long as the control motor is of sufilcient size to drive the other motors. Also it is understood that the details of the invention may be varied within the scope of the following claims.

I claim as my invention:

1. In a motor system of the electric gear type, a plurality of electric motors having rotor and stator members, a source of alternating current power, a primary distributed winding upon one member of each motor and energized from said source of power to produce a single phase alternating current field in each said motor, a phase wound secondary winding upon the other of said members of each motor, the secondary windings of said motors having the same number of phases and being connected together to provide for the flow of power currents between and through said secondary windings when the rotors of said motors are relatively displaced, and a tertiary distributed winding upon said one of said members of each motor, the tertiary windings of said motors being connected together, each tertiary winding having the connections thereto displaced with respect to the connections to the primary winding of the same motors and having its conductors positioned upon said motor to provide for the flow of substantial power currents between and through said tertiary windings when the rotors of said motors are relatively'displaced.

2. In a motor system of the electric gear type, a plurality of electric motors having rotor and stator members, a source of alternating current power, a primary distributed winding upon one member of each motor and energized from said source of power to produce a single phase alternating current field in each said motor, a phase wound secondary winding upon the other of said members of each motor, the secondary windings of said motors having the same number of phases and being connected together to provide for the flow of power currents between and through said secondary windings when the rotors of said motors are relatively displaced, and a tertiary distributed winding upon said one of said members of each motor, the tertiary windings of said motors being connected together, each tertiary .winding having the connections thereto dlsplaced with respect to the connections to pri mary winding of the same motor and having its conductors positioned upon said motor to provide for the flow of substantial power currents between and through said tertiary windings when the rotors of said motors are relatively displaced, a source of direct current, 'said tertiary windings being connected to and energized from said source of d rect current to establish a direct current field in said motors.

3. In a motor system of the electric gear type, a plurality of electric motors having rotor and stator members, a source of alternating current power, a primary distributed winding upon one member of each motor and energized from said source of power to produce a single phase alternating field in each said motor, the energization of said primary winding being insufiicient to produce normal saturation of the iron of said motor adjacent said primary winding, a phase wound secondary winding upon the other of said members of each motor, a source of direct current power, a tertiary winding upon said one of said members of each motor, said third winding being distributed and being energized from said source of direct current power to produce a di rect current field in said motor and increase the saturation of said iron adjacent said primary winding to normal saturation, the secondary windings of said motors having the same number of phases and being connected together to provide'i'or the flow of power currents between and through said secondary windings when said primary and third windings are energized and the rotors of said motors are relatively displaced.

4. In a motor system of the electric gear type, a plurality of electric motors having rotor and stator members, a source of alternating current power, a primary distributed winding upon one member of each motor and energized from said source of power to produce an alternating current field in each said motor, a phase wound secondary winding upon the other of said meta-- bers of each motor, the secondary windings of said motors having the same number of phases and being connected together to provide for the flow of power currents between and through said secondary windings when the rotors of said motors are relatively displaced, and a tertiary distributed winding upon said one of said members of each motor, the tertiary windings of said motors being connected together, each tertiary winding having the connections thereto displaced with respect to the connections to the primary winding of the same motors and having its conductors positioned upon said motor to provide for the flow of substantial power currents between and through said tertiary windings due to modi fication of said field of each motor by currents in said secondary windings when the rotors of said motors are relatively displaced.

5. In a motor system of the electric gear type, a plurality of. electric motors having rotor and stator members, a source of alternating current power, a primary distributed winding upon one member of each motor and energized from said source of power-to produce an alternating current field in each said motor, a phase wound secondary winding upon the other of said memhers oi each motor, the secondary windings of said motors having the same number of phases and-being connected together to provide 'for the flow of power currents between and through said secondary windings when the rotors of said motors are relatively displaced, and a tertiary distributed winding upon said one of said members of each motor, the tertiary windings of said motors being connected together, each tertiary winding having the connections thereto displaced with respect to the connections to primary winding oi the same motor and having its conductors positioned upon said motor to provide for the flow of substantial power currents between and through said tertiary windings due to modifica- .tion of said field of each motor by currents in said secondary windings when the rotors of said motors are relatively displaced, a source of direct current, said tertiary windings being connected to and energized from said source of direct current to establish a direct current field in said motors.

CHARLES P. SWEENY. 

